The Uruguay striker has netted 19 goals in 13 Barclays Premier League appearances this season after serving a 10-match suspension for biting Chelsea defender Branislav Ivanovic in April.
After three wins in the opening five games, Suarez's return has helped the Reds, last champions in 1989/90, into the top four.
"He didn't start the season, with suspension, and after that the numbers are fantastic," Mourinho said.
"When he came back, it was a big plus. But let's be fair: Liverpool did very well without him when he was suspended."
Not playing in European competition this term means Liverpool, under Brendan Rodgers, have a sole focus, while Chelsea, Manchester United, Manchester City and Arsenal are still in the Champions League.
Mourinho, who employed Rodgers at Chelsea, said: "I think they can (win the Premier League), because they are good, because Brendan is good, because they have time to prepare the team tactically, because they are not involved in the heat of the knock-out situation in the Champions League or even Europa League.
"These (Chelsea) players are going to play 60 matches. Liverpool will play 40 matches. It's a big difference.
"Quality, plus ambition, plus this advantage, so yes (they are contenders)."
With Liverpool, who finished seventh last term, among the contenders, Mourinho recognises achieving Chelsea's first goal is a stiff challenge.
"This year the pressure will be not just to win the title, but also to get top four (and Champions League qualification)," Mourinho added.
"Man City are the big, big, big favourites. Liverpool are on holidays one season: one week to prepare a match, play the match, one more week to prepare the next match. This is an advantage, an unbelievable advantage.
"And Man United, in spite of being a few points behind, are the reality of the last years.
"Arsenal are like us. For many years they've not been at the top of the league. Chelsea won the league a few years' ago, but in the last two leagues were 25 and 14 points off the leaders.
"For us and for Arsenal we have to try and do the best we can. We'll do our job, we'll try to finish top four. And if we manage to be in the top four, let's see what we can do (in terms of the title)."
Chelsea will be tested on Sunday by a Liverpool side beaten by Manchester City on Thursday.
Suarez sunk his teeth into Ivanovic in the most recent meeting between the teams, and with the on-field incident going unpunished, Suarez netted a 97th-minute equaliser to earn Liverpool a draw.
Ivanovic has moved on and Mourinho was not prepared to be drawn into the controversy.
Mourinho added: "Iva is a big guy. He's not a Mickey Mouse player who complains at little things. This was a big thing, but Iva thinks it's something from the past. Everyone moves on."
It was put to Mourinho that having a striker like Suarez would be the difference for Chelsea, whose front three of Fernando Torres, Samuel Eto'o and Demba Ba have scored five times between them in the Premier League this season.
"That's what it is," Mourinho said.
Mourinho's meetings with Liverpool bring recollections of intense rivalry in cup competitions both domestically and Europe, where Luis Garcia's 'ghost' goal was the most controversial of all the major incidents.
With Rodgers, one of Mourinho's "best friends in the game", now in charge, the personal nature of the rivalry may have lessened.
Mourinho said: "He's doing fantastically. But he's training every week in a calm way. Every day. Maybe twice a day.
"He needs to work well, because you can work a lot and work bad, but he has a big advantage compared to other teams.
"Not to be involved in European competition gives them a big advantage: not in terms of resting, in terms of working. They can work."